Levothyroxine sodium is a synthetically manufactured form of the natural thyroid hormone tetraiodothyronine (T-4). Thyroid hormones are primarily responsible for regulating the body’s metabolic rate, and play a vital role in the body’s utilization of protein, fat, and carbohydrates. Levothyroxine sodium is used medically to treat cases of hypothyroidism, which is characterized by insufficient natural production of thyroid hormones.This may manifest itself with a number of symptoms including loss of energy, lethargy, weight gain, hair loss, and changes in skin texture. Levothyroxine sodium is considered a slow-acting medication, and may take up to 4 to 6 weeks before full therapeutic levels are reached in the blood. It is also the most commonly prescribed thyroid medication in the world, and is considered to be the standard form of treatment for most cases of hypothyroidism.
The action of levothyroxine sodium is very similar to that of the popular thyroid preparation Lionine -T3 (liothyronine sodium). Lionine -T3 is slightly different in structure, however, being a synthetic form of the thyroid hormone triiodothyronine (T-3). A healthy individual with have sufficient levels of both T-3 and T-4 thyroid hormones present in their body. T-3 is considered the primary active form of thyroid hormone, while T4 serves mainly as a reserve for T3, exerting most of its metabolic activity via conversion to T3 in peripheral tissues. T3 is regarded as having an effect that is roughly four times stronger than that of T-4 on a milligram-for-miIIigram basis. Likewise, Lionine -T3 is considered to be a more potent form of thyroid medication, both with regard to activity and side effect potential.
Levothyroxine sodium is valued by many drug-using athletes and bodybuilders for its ability to stimulate the metabolic rate and support the breakdown of body fat stores. It is usually taken during a period of calorie restriction (”cutting”), when the individual is focused on fat loss or increasing muscle definition. It is often thought that the use of thyroid drugs can support fat loss at a higher level of caloric intake than would otherwise be possible without the drugs, adding to their perceived value among the communities. Anabolic steroids are generally used in conjunction with these hormones, and many believe that the metabolism boosting effect of these drugs may Produce faster gains in muscle mass. The drugs, however, have yet to be widely proven or accepted for this purpose.